The invention is generally concerned with gusseted bags, and more particularly thermoplastic grocery bags of the type frequently supplied in multiple bag packs for a selected separable dispensing of the individual bags. Such bags may incorporate integral handles and opposed side walls, one or both of which are inwardly folded between the front and rear bag walls to define bag expanding gussets. With side gussets, the gussets extend the full height of the individual bag both to enhance the strength of the handles and to allow for a lateral outward expansion of the bag, when loaded, to increase the carrying capacity thereof.
Another form of known bag incorporates a bottom gusset defined by an inwardly folded bottom having the opposed ends thereof sealed between the corresponding sealed side edges of the front and rear bag walls.
Bags of the type involved herein are frequently formed by utilizing flattened tube portions selectively severed from a length of tubing of appropriate material and heat sealed along the overlying opposed edges thereof.
In bags with side gussets, wherein the bags are heat sealed along the upper and lower edges thereof, opposed full height sections of the tube portions are inwardly folded to form the side walls or gussets. The upper and lower ends of the inwardly folded side walls or gussets are in turn heat sealed to and between the upper and lower edges of the opposed front and rear panels. An appropriate mouth-defining cutout is normally made through the sealed upper portion of the bag with the cutout simultaneously defining both the opposed handles and a central bag mouth.
In bags with bottom gussets, that is a gusset forming the bottom or bottom wall of the bag, the flattened tube portion is heat sealed along the opposed sides thereof with a transverse section inwardly folded between the front and rear bag walls to define the bottom gusset. The opposed ends of the bottom gusset are heat sealed between the heat sealed side edges of the front and rear bag walls.
Plastic bags of the type described above are common in the art as noted in the following patents:
U.S. Pat. No. 3,352,411, Schwarzkopf PA1 U.S. Pat. No. 3,774,838, Christie PA1 U.S. Pat. No. 4,062,170, Orem PA1 U.S. Pat. No. 4,165,832, Kuklies et al PA1 U.S. Pat. No. 4,199,122, Christie PA1 U.S. Pat. No. 4,476,979, Reimann et al PA1 U.S. Pat. No. 4,480,750, Dancy
While such bags have, in general, found ready acceptance in the marketplace for a variety of reasons, a troublesome problem has appeared with regard to the tendency of the gussets to "blow out", particularly when large and heavy items are placed within the bag. This involves, in regard to side wall gussets, a "peeling" or tearing loose of the lower end of the gusset from the heat sealed lower seam with the gusset expanding outward and presenting an enlarged open lower end which destroys the integrity of the bag and allows the bagged items to fall therethrough. A similar problem arises with regard to bottom wall gussets wherein both of the opposed seam-sealed ends tend to tear loose and form enlarged openings. Basically, such a tearing takes place when a large and/or heavy load is put in the bag and an excessive force is put on the gusset ends at the expanding bottom of the bag. Such a force can occur under loads which could normally be considered well within the capability of the bag were it not for this tearing action at the lower ends of the gussets.